This invention relates to a ZIF (Zero Insertion Force) connector and, in particular, to a ZIF connector comprising, as a set of contact elements, a flexible contact sheet such as an FPC (Flexible Printed Circuit) and an FFC (Flexible Flat Cable).
A ZIF connector using a flexible contact sheet as a set of contact elements is known in the art. For example, ZIF connectors of the type are disclosed in Japanese Unexamined Patent Publications (JP-A) Nos. 3-30273, 3-257775, and 4-501338. However, those ZIF connectors are complicated in structure and therefore difficult to be reduced in size. The operation for connecting or disconnecting two objects (such as printed circuit boards) having such ZIF connectors has at least two step handling motions. In other words, the two objects can not be connected in a single step handling motion and, once connected, can not be disconnected in a single step handling.
In view of the above, an improved ZIF connector is disclosed in Japanese Patent Publication (JP-B) No. 2717393 (see FIGS. 6 through 9). The ZIF connector disclosed in the Japanese patent comprises a combination of first and second connector members mounted to first and second objects, respectively.
The first connector member comprises a first housing, a pair of urging plates, a slider, and a pair of flexible contact sheets. The first housing is adapted to be releasably coupled to the second connector member in a predetermined direction. Each of the urging plates has a jointed portion to which a part of the flexible contact sheet is jointed. The urging plates are attached to the first housing to be elastically deflectable in its thickness direction and to be elastically returned to a predetermined position. The slider is adapted to be fixed on the first object and is attached to the first housing to be relatively slidable in the predetermined direction. The slider has a pair of cam portions to be engaged with the urging plates to elastically deflect the urging plates when the slider slides in the first housing towards the second connector member. Each of the flexible contact sheets comprises an insulator film and a conductor pattern which comprises a plurality of conductor lines as contact elements embedded in the insulator film. The each flexible contact sheet has a supported portion supported by an inner insulator supported in the first housing, an insert portion to be inserted into the second connector member, and a connect portion to be electrically connected to the first object. The conductor pattern is partially exposed in one surface at the insert portion. The insert portion is jointed to the jointed portion of each of the urging plates. The remaining portions of the flexible contact sheet, that is, intermediate portions between the insert portion and the supported portion and between the connect portion and the supported portion, are connected or attached to nothing. Therefore, the remaining portions are movable freely. Therefore, the intermediate portions are collectively referred to as a freely movable sheet portion.
The second connector member comprises a second housing and a plurality of contacts. The second housing is adapted to be attached to the second object and releasably coupled to the first housing in the predetermined direction. Each of the contacts is disposed in the second housing and comprises a terminal portion to be electrically connected to the second object, and a contact portion to face, in a substantially untouched condition, the insert portion positioned by the jointed portion of the urging plate located at the predetermined position when the first and the second housings are coupled to each other and to be brought into contact with the conductor pattern when the urging plate is elastically deflected by the cam portion.
When the first and the second connector members are coupled and released in the predetermined direction, the slider attached to the first object slides with respect to the first housing in the predetermined direction.
With the above-mentioned structure, the freely movable sheet portion of the flexible contact sheet is tightly bent and returned to a relaxed state every time when the first and the second connector members are coupled and released. Thus, the flexible contact sheet is repeatedly bent and relaxed at every coupling and releasing operations of the ZIF connector.
Since the freely movable sheet portion of the flexible contact sheet is repeatedly bent as described above, the freely movable sheet portion tends to be damaged. In particular, the conductor pattern at the freely movable sheet portion is readily damaged.
After the ZIF connector is connected, the freely movable sheet portion of the flexible contact sheet is kept tightly bent. Therefore, the freely movable sheet portion is easily damaged even if the coupling and the releasing operations are not repeated.
Upon connection of the ZIF connector, the first connector member can not be connected to the second connector member if the cam portion of the slider is engaged with the urging plate. However, the ZIF connector has no mechanism for inhibiting the engagement between the cam portion of the slider and the urging plate during connection of the ZIF connector. Furthermore, no mechanism is provided to maintain the first and the second connector members in a connected state after the ZIF connector is connected. Therefore, the first connector member may not be smoothly connected to the second connector member upon connecting of the ZIF connector. After the first connector member is connected to the second connector member, the first connector member may easily be released from the second connector member when subjected to external force.
In the ZIF connector, the flexible contact sheet is positioned with respect to the first housing simply by inserting the inner insulator into a gap between the first housing and the slider. Therefore, the flexible contact sheet is easily dislocated. If the ZIF connector is reduced in size, the flexible contact sheet may possibly be brought into false contact with the contacts of the second connector member.